A conventional water bottle, a canteen or a flask generally has a rounded body, a narrow neck, a stopper and a cup. They have several disadvantages as follows.
1. The stopper and the cup have to be removed first.
2. In case the bottle should be turned upside down with the stopper removed, water therein would quickly escape.
3. The bottle may be broken easily if it is carelessly dropped on the ground, especially when filled with water.